Acoustic metamaterial sound absorption structure and transformer substation equipment noise reduction device

Abstract

The invention discloses an acoustic metamaterial sound absorption structure and a transformer substation equipment noise reduction device, and relates to the technical field of transformer substation noise reduction, the acoustic metamaterial sound absorption structure comprises two shells arranged in parallel and a honeycomb structure arranged in the two shells; the honeycomb structure comprises a plurality of cavity units, the cavity units are periodically and continuously arranged, an opening of each cavity unit faces one shell, a hole is formed in the position, corresponding to the opening of each cavity unit, of one shell, and a Helmholtz resonance cavity is formed by each cavity unit, the two shells and the holes. Low-frequency-band noise enters the Helmholtz resonance cavity through the holes and resonates with the inherent frequency of the cavity, potential energy of sound waves is converted into heat energy to be counteracted, therefore, propagation of the sound energy is weakened, the sound waves are continuously consumed in the propagation process, the noise is further absorbed, and the problem that an existing noise reduction device is poor in low-frequency noise reduction effect is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of noise reduction in transformer substations, and in particular to an acoustic metamaterial sound absorbing structure and a noise reduction device for transformer substation equipment. Background Art

[0002] Substations are power facilities that transform voltage, receive and distribute electric energy, control the flow of electricity, and adjust voltage in power systems. Substations connect power grids of various voltage levels through transformers. Substations can be roughly divided into step-up substations and step-down substations. Step-up substations are located near power plants and transmit the electric energy generated by power plants to distant power consumption areas by increasing the voltage. Step-down substations are located in power consumption areas and reduce the high voltage of the electric energy sent by step-up substations to the corresponding voltage level as needed, and then distribute the electric energy to power users in the area.

[0003] However, during the long-term operation of the substation, the various electrical equipment running inside is prone to generate noise. At present, the equipment that generates noise sources in the substation is mainly transformers, reactors and other equipment; for the noise of substation equipment, the main noise reduction materials used in the existing technology are mostly traditional materials such as rock wool, glass wool, polyester fiber sound-absorbing panels, steel plates, aluminum plates, etc. These materials can effectively reduce high-frequency noise, and the noise reduction effect on high-frequency noise is significant, but the substation equipment emits full-band noise, mainly medium and low frequencies. Due to the low frequency, long wavelength and strong penetration of low-frequency noise, the existing noise reduction technology is difficult to effectively isolate the low-frequency noise in the substation. Summary of the invention

[0004] In order to solve the problem that it is difficult to effectively isolate low-frequency noise in a substation in the prior art.

[0005] The purpose of the present invention is to adopt the following technical solutions to achieve:

[0006] In a first aspect, the present invention provides an acoustic metamaterial sound absorbing structure, comprising two shells arranged parallel to each other and a honeycomb structure arranged in the two shells;

[0007] The honeycomb structure includes a plurality of cavity units, which are periodically and continuously arranged, the opening of each cavity unit faces one of the shells, and a hole is provided at a position corresponding to the opening of each cavity unit, and the cavity unit, the two shells and the hole form a Helmholtz resonance cavity.

[0008] Preferably, the holes are divided into first holes and second holes, the diameter of the first holes is larger than the diameter of the second holes; and the first holes and the second holes are distributed alternately.

[0009] Furthermore, an insertion tube extending into the cavity unit is fixed on the second hole.

[0010] Preferably, the cross-sectional shape of the cavity unit includes a regular hexagon, a parallelepiped or an axisymmetric hexagon.

[0011] Preferably, the cavity unit and the shell are made of aluminum-manganese alloy.

[0012] Preferably, the sound absorption coefficient of the Helmholtz resonance cavity is calculated as follows:

[0013]

[0014] Where α is the sound absorption coefficient of a single Helmholtz resonance cavity; Z s is the surface acoustic impedance of the Helmholtz resonance cavity.

[0015] Furthermore, the surface acoustic impedance Z of the Helmholtz resonance cavity is s The calculation formula is:

[0016] Z s =δ2(Z′ n / φ+Z c ) / Z0;

[0017] In the formula, δ2 is the correction coefficient of the cavity wall thickness on the acoustic impedance, δ2 = S A / S c , S A is the cross-sectional area of ​​the external cavity, S c is the cross-sectional area of ​​the internal air cavity, φ is the porosity, φ=S e / S c , S e is the cross-sectional area of ​​the insertion tube, Z n ' is the characteristic impedance of the end of the insertion tube; Z c is the cavity characteristic impedance of the Helmholtz resonance cavity; Z0 is the characteristic impedance of air.

[0018] Furthermore, the characteristic impedance Z of the end of the insertion tube is n The calculation formula of ′ is:

[0019]

[0020] In the formula, Z n is the insertion tube impedance; y is a dimensionless constant representing the ratio of the insertion tube radius to the viscous boundary thickness, d is the diameter of the insertion tube; μ0 is the kinematic viscosity of the air, j is the imaginary unit, ω is the angular frequency, ω=2πf, f is the sound wave frequency, and ρ0 is the air density.

[0021] Furthermore, the insertion tube impedance Z n The calculation formula is:

[0022]

[0023] Where j is an imaginary unit, ω is the angular frequency, ω=2πf, f is the sound wave frequency, ρ0 is the air density, l is the height of the entire insertion tube, ν0 is the air viscosity, ν0=μ0 / ρ0, μ0 is the kinematic viscosity of the air, Λ is the viscous characteristic length, q0=μ0 / σ,α ∞ is the curvature, χ is the curvature coefficient, σ is the static flow resistivity, σ=32μ0 / d 2 , d is the diameter of the insertion tube.

[0024] Furthermore, the cavity characteristic impedance Z of the Helmholtz resonance cavity is c The calculation formula is:

[0025] Z c =-jZ0cot(k0δ1h)

[0026] Where j is an imaginary unit, ω is the angular frequency, Z0 is the characteristic impedance of air, Z0 = ρ0c0, ρ0 and c0 are air density and sound speed respectively, k0 is the air wave number, k0 = ω / c0, δ1 = (V c -V e ) / V c , V c is the air volume of the cavity, V e is the volume of air in the inserted tube, V c =S c (L-2t1), V e =S e (l e -t1), S e is the cross-sectional area of ​​the insertion tube, S c is the cross-sectional area of ​​the internal air cavity, t1 is the cavity thickness, L is the height of the cavity, l e represents the overall height of the insertion tube, δ1 is the correction coefficient considering the effect of the total surface of the cavity on the acoustic impedance, and h is the height of the insertion tube in the cavity.

[0027] In a second aspect, the present invention proposes a noise reduction device for substation equipment, comprising an acoustic metamaterial sound-absorbing structure as described in any one of the above items, and a sound insulation structure fixed to the bottom of the acoustic metamaterial sound-absorbing structure; the hole on the shell of the acoustic metamaterial sound-absorbing structure faces the sound source side.

[0028] Preferably, an elastic member is fixed between the acoustic metamaterial sound absorbing structure and the sound insulating structure.

[0029] Preferably, the acoustic metamaterial sound absorbing structure and the sound insulating structure are installed inside an assembled shell, and the assembled shell is a rectangular shell with an open top.

[0030] Furthermore, the bottom of the assembled shell extends outward to form a flange.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] The present invention provides an acoustic metamaterial sound-absorbing structure, wherein a plurality of cavity units are periodically and continuously arranged to form a honeycomb structure, and the honeycomb structure is installed in two parallel shells, the opening of each cavity unit faces one of the shells, and a hole is provided at a position corresponding to the opening of each cavity unit, and the cavity unit, the two shells and the hole form a Helmholtz resonance cavity; low-frequency noise enters the Helmholtz resonance cavity through the hole, and when the sound wave of the noise hits the surface of the cavity, the natural frequency of the Helmholtz resonance cavity is close to the frequency of the sound wave, and resonance occurs, causing the energy of the sound wave to be absorbed by the material, converting the potential energy of the sound wave into heat energy to offset it, thereby weakening the propagation of sound energy, causing the noise sound wave to be continuously consumed during the propagation process, and then absorbing the noise. The present invention can effectively control low-frequency noise, isolate the propagation of low-frequency noise, and avoid the problem that low-frequency noise cannot be effectively isolated.

[0033] The present invention provides a noise reduction device for substation equipment. By combining an acoustic metamaterial sound absorption structure with excellent low-frequency sound absorption performance and a sound insulation structure with good high-frequency sound insulation performance into a full-band noise reduction device structure, the low-frequency noise and high-frequency noise generated by the substation equipment can be effectively absorbed and isolated. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a three-dimensional schematic diagram of a sound-absorbing structure of an acoustic metamaterial in Example 1 of the present invention;

[0035] Figure 2 This is a three-dimensional schematic diagram of a honeycomb structure of an acoustic metamaterial sound-absorbing structure in Example 1 of the present invention;

[0036] Figure 3 This is a three-dimensional schematic diagram of the shell structure of an acoustic metamaterial sound-absorbing structure in Example 1 of the present invention;

[0037] Figure 4 This is a schematic structural diagram of a noise reduction device for substation equipment in Embodiment 2 of the present invention;

[0038] Figure 5 This is a schematic diagram of the assembled shell structure of a noise reduction device for substation equipment in Example 2 of the present invention;

[0039] Figure 6 This is a schematic diagram of a frame turning structure of a noise reduction device for substation equipment in Embodiment 2 of the present invention;

[0040] Figure 7 A side view of a noise reduction device for substation equipment in Embodiment 2 of the present invention;

[0041] Figure 8 It is a partial enlarged side view of a noise reduction device for substation equipment in Example 2 of the present invention;

[0042] Explanation of the reference numerals: 1 is a shell; 2 is a honeycomb structure; 3 is an adhesive; 4 is a hole; 5 is a sound insulation structure; 6 is an elastic member; 7 is a flange; and 8 is an assembled shell. DETAILED DESCRIPTION

[0043] In the following, only some exemplary embodiments are briefly described. As those skilled in the art will appreciate, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and descriptions are considered to be exemplary and non-restrictive in nature.

[0044] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0045] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0046] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or a communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0047] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0048] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0049] It should also be understood that the terms used in the present specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0050] It should be further understood that the term "and / or" used in the present description and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0051] Various structural schematic diagrams of the embodiments disclosed in the present invention are shown in the accompanying drawings. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clear expression. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may additionally design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0052] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0053] Example 1

[0054] like Figures 1 to 3 As shown, the present invention proposes an acoustic metamaterial sound absorbing structure, which includes a shell 1 and a honeycomb structure 2.

[0055] like Figure 1As shown, the honeycomb structure 2 is a continuous combination of multiple cavity units formed by periodic topology along a two-dimensional plane. The honeycomb structure 2 is arranged in two shells 1 parallel to each other, and the opening of each cavity unit faces one of the shells 1, and one of the shells 1 is provided with a hole 4 at a position corresponding to the opening of each cavity unit. The cavity unit corresponds to the two shells 1 and the hole 4 to form a Helmholtz resonance cavity.

[0056] In the embodiment of the present invention, two shells 1 arranged in parallel to each other are fixed on a honeycomb structure 2 with multiple cavity units distributed thereon, thereby forming an acoustic metamaterial sound absorption structure having a honeycomb sandwich structure, and holes 4 are provided on the shell 1 above each cavity unit. By providing a through hole facing the sound source side on the shell 1 above the hexagonal cavity unit, the shell on the other side plays a sealing role, so that the internal cavity of the cavity unit forms a honeycomb Helmholtz resonance cavity; low-frequency noise enters the honeycomb Helmholtz resonance cavity through the hole, and based on the principle of local resonance, the low-frequency noise is absorbed by resonance, which can effectively control the low-frequency noise, isolate the propagation of low-frequency noise, and avoid the problem that low-frequency noise cannot be effectively isolated, and has excellent low-frequency sound absorption performance.

[0057] Specifically, in the embodiment of the present invention, a through hole is provided on the side of the shell 1 facing the sound source, the hole 4 is located at the center of a single cavity unit, and the aperture of the hole 4 ranges from 8 mm to 14 mm.

[0058] like Figure 3 As shown, in the embodiment of the present invention, the hole 4 is divided into a first hole and a second hole, the diameter of the first hole is larger than the diameter of the second hole, and the first hole and the second hole are alternately distributed along the periodic distribution direction of the cavity unit. An insertion tube is arranged inside the second hole, and the insertion tube extends into the honeycomb Helmholtz resonance cavity. In the embodiment of the present invention, the size of the hole 4 is adjusted to change the sound absorption performance, mainly absorbing low-frequency noise, and absorbing sound waves by utilizing the principle of local resonance.

[0059] like Figure 2As shown, the cross-sectional shape of a single cavity unit in the honeycomb structure in the embodiment of the present invention is preferably a hexagon, which may be a regular hexagon, a parallelepiped, or an axisymmetric hexagon. The hexagonal single cavity units are arranged in a two-dimensional regular pattern to form an acoustic metamaterial sound-absorbing structure. The arrangement may be that the six sides of the cavity unit are respectively connected to the corresponding sides of the six cavity units surrounding the cavity unit, that is, each hexagonal cavity unit can be adjacent to the six surrounding cavity units and connected to the side wall of a common side. Compared with other shapes, the hexagonal cavity unit used in the embodiment of the present invention has excellent mechanical stability. When the noise sound wave propagates inside the hexagonal cavity and hits the cavity surface, it can be evenly dispersed and has high structural stability. In addition, the hexagonal cavity unit has a large cavity area, which can be closely arranged, minimizes the gaps, and realizes efficient use of space.

[0060] An acoustic metamaterial sound absorbing structure provided in an embodiment of the present invention generally uses an aluminum-manganese alloy, and in the embodiment of the present invention, 3003 rust-proof aluminum is preferred, wherein the wall thickness of the hexagonal cavity unit is 0.1 mm. The shell 1 uses an aluminum-manganese alloy, and in the embodiment of the present invention, 5052AH14 rust-proof aluminum is preferred, with a thickness of 2 mm on the side facing the sound source opening and 1 mm on the side facing away from the sound source.

[0061] In the embodiment of the present invention, an aluminum-manganese alloy is used to form a hexagonal cavity unit, which is periodically distributed to form a honeycomb structure 2; the acoustic metamaterial sound absorption structure has holes facing the sound source side, and a Helmholtz resonance cavity is formed inside the hexagonal cavity unit, which uses resonance to absorb sound and reduce low-frequency noise. In addition, the acoustic metamaterial sound absorption structure formed by the aluminum-manganese alloy has a low density, light weight, and is easy to install.

[0062] In the embodiment of the present invention, the honeycomb structure 2 and the shell 1 can be fixedly connected by welding, adhesive bonding, etc., or can be integrally formed by 3D printing, casting, etc.

[0063] The acoustic metamaterial sound absorption structure in the embodiment of the present invention can also be used to absorb high-frequency noise. The sizes of the Helmholtz resonance chambers corresponding to different frequencies are different. The above structural parameters are suitable for low-frequency noise. When absorbing high-frequency noise, the size of the cavity unit, the aperture of the opening, the size of the tube in the hole, and the arrangement of the holes are designed according to the frequency of the high-frequency noise to form a Helmholtz resonance chamber with different structural parameters from the low-frequency noise. Based on the principle of local resonance, when the sound wave hits the surface of the material, if the natural frequency of the material is close to the frequency of the sound wave, resonance will occur, causing the energy of the sound wave to be absorbed by the material, and the potential energy of the sound wave is converted into heat energy to offset it. By designing the structure of the high-frequency noise Helmholtz resonance chamber, the frequency in the Helmholtz resonance chamber is close to the high-frequency noise frequency that is to be reduced, so as to achieve resonance and increase the sound absorption coefficient.

[0064] Compared with conventional sound-absorbing materials, such as sound-absorbing cotton, the acoustic metamaterial sound-absorbing structure in the embodiment of the present invention designs the size of the cavity unit, the aperture of the opening, the size of the tube in the hole, and the arrangement of the holes for specific frequencies. The holes are for the sound to enter the acoustic metamaterial sound-absorbing structure (i.e., inside the hexagonal structure). Each cavity unit is an independent space with a hole on one side. A Helmholtz resonance cavity is formed inside the cavity unit. After the sound enters the Helmholtz resonance cavity, the Helmholtz resonance cavity resonates. By designing the honeycomb size, the aperture of the opening, the size of the tube in the hole, and the arrangement of the holes, the cavity can resonate with a frequency close to the low-frequency noise, and the two cancel each other out to achieve the effect of resonant sound absorption.

[0065] In the embodiment of the present invention, the honeycomb size is designed, and different size designs will have different effects on noise control in different frequency bands. The cavity unit in the embodiment of the present invention is preferably a regular hexagon with a side length of 5 cm and a wall thickness of 0.1 mm, which is used to absorb noise in the frequency range of 100 Hz to 1100 Hz. The size of the cavity unit, the aperture of the opening, and the length of the tube in the hole will affect the sound absorption performance. These factors can be designed to obtain the optimal structure corresponding to different frequencies.

[0066] In the embodiment of the present invention, the structure of the cavity unit is designed by the following formula. By exploring the honeycomb structure design when the highest sound absorption coefficient is achieved at different sound wave frequencies, the honeycomb cavity structure (including the size of the honeycomb and the size of the insertion tube) is designed mainly by the following formula, and then the sound absorption coefficient of the honeycomb cavity to a specific frequency is adjusted.

[0067] The sound absorption coefficient α of the Helmholtz resonance cavity in the acoustic metamaterial sound absorption structure can be calculated by the following formula:

[0068]

[0069] Where α is the sound absorption coefficient of a single Helmholtz resonance cavity; Z s is the surface acoustic impedance of the Helmholtz resonance cavity.

[0070] The surface acoustic impedance Z of the Helmholtz resonance cavity s The calculation formula is:

[0071] Z s =δ2(Z′ n / φ+Z c ) / Z0

[0072] In the formula, δ2 is the correction coefficient of the cavity wall thickness on the acoustic impedance, δ2 = S A / S c , S A is the cross-sectional area of ​​the external cavity, S cis the cross-sectional area of ​​the internal air cavity, φ is the porosity, φ=S e / S c , S e is the cross-sectional area of ​​the insertion tube, Z n ' is the characteristic impedance of the end of the insertion tube; Z c is the characteristic impedance of the Helmholtz resonance cavity; Z0 is the characteristic impedance of air.

[0073] Where, the characteristic impedance Z at the end of the insertion tube is n The calculation formula of ' is:

[0074]

[0075] In the formula, Z n is the insertion tube impedance; y is a dimensionless constant representing the ratio of the insertion tube radius to the viscous boundary thickness, d is the diameter of the insertion tube; μ0 is the kinematic viscosity of air, μ0 = 1.81 × 10 -5 Pa·s, j is the imaginary unit, ω is the angular frequency, ω=2πf, f is the sound wave frequency, ρ0 is the air density, ρ0=1.29kg / m 3 .

[0076] Where, the insertion tube impedance Z n The calculation formula is:

[0077]

[0078] Where j is the imaginary unit, ω is the angular frequency, ω = 2πf, f is the sound wave frequency, ρ0 is the air density, ρ0 = 1.29 kg / m 3 , l is the height of the entire insertion tube, ν0 is the air viscosity, ν0 = μ0 / ρ0, μ0 is the kinematic viscosity of air, μ0 = 1.81 × 10 -5 Pa·s, Λ is the characteristic length of viscosity, q0=μ0 / σ,α ∞ is the curvature, α ∞ =1, χ is the bending coefficient, χ=1, σ is the static flow resistivity, σ=32μ0 / d 2 , d is the diameter of the insertion tube.

[0079] Among them, the cavity characteristic impedance Z of the Helmholtz resonance cavity is c The calculation formula is:

[0080] Z c =-jZ0cot(k0δ1h)

[0081] Where j is an imaginary unit, ω is the angular frequency, Z0 is the characteristic impedance of air, Z0 = ρ0c0, ρ0 and c0 are air density and sound speed respectively, k0 is the air wave number, k0 = ω / c0, δ1 = (V c -V e ) / V c , V c is the air volume of the cavity, V e is the volume of air in the inserted tube, V c =S c (L-2t1), V e =S e (l e -t1), S e is the cross-sectional area of ​​the insertion tube, S c is the cross-sectional area of ​​the internal air cavity, t1 is the cavity thickness, L is the height of the cavity, l e represents the overall height of the insertion tube, δ1 is the correction coefficient considering the effect of the total surface of the cavity on the acoustic impedance, and h is the height of the insertion tube in the cavity.

[0082] Embodiment 2:

[0083] like Figure 4 As shown, the present invention based on the same inventive concept also provides a noise reduction device for substation equipment, including: a sound absorbing and insulating structure, the sound absorbing and insulating structure is a composite of an acoustic meta-material sound absorbing structure and a sound insulating structure 5; the acoustic meta-material sound absorbing structure is a rectangular parallelepiped structure composed of a honeycomb structure 2 and a shell 1, the honeycomb structure 2 is a continuous combination formed by a periodic topology of a plurality of cavity units, and the shell 1 is fixed to the upper and lower openings of the honeycomb structure 2; a plurality of holes 4 are opened on the shell 1 on one side, and the shell on the other side is sealed; the holes 4 and the internal cavity of the cavity unit and the two shells 1 form a Helmholtz resonance cavity.

[0084] The shell 1 in the embodiment of the present invention wraps up the cavity unit, and each honeycomb forms an independent space. After opening the hole facing the sound source side, the honeycomb becomes a spatial structure with only one side opening. This structure is called a Helmholtz resonance cavity, which offsets the sound waves of a specific frequency through the resonance of the cavity, thereby reducing the noise of a specific frequency. In addition, in the embodiment of the present invention, the acoustic metamaterial sound absorption structure and the sound insulation structure 5 are combined to form a full-band high-efficiency noise reduction device structure, which can effectively absorb and isolate high-frequency noise and low-frequency noise.

[0085] The acoustic metamaterial sound absorption structure in the embodiment of the present invention is composed of a periodic array of hexagonal single cavity units. The acoustic metamaterial sound absorption structure is designed based on the principle of local resonance and can effectively control noise in the low-frequency band. The acoustic metamaterial sound absorption structure can absorb low-frequency noise during the propagation of low-frequency noise, avoiding the problem that low-frequency noise cannot be effectively absorbed. The acoustic metamaterial sound absorption structure with excellent low-frequency sound absorption performance and the sound insulation material with good high-frequency sound insulation performance are combined into a full-band high-efficiency noise reduction device structure to solve the problem that the existing noise reduction device has poor noise reduction effect on low-frequency noise.

[0086] Specifically, Figure 7 and Figure 8 As shown, an elastic member 6 is provided between the acoustic meta-material sound absorbing structure and the sound insulation structure 5 in the embodiment of the present invention. The elastic member 6 is provided to reduce the vibration between the acoustic meta-material sound absorbing structure and the sound insulation structure 5, and to avoid the transmission of noise. The elastic member 6 in the embodiment of the present invention is not only provided between the acoustic meta-material sound absorbing structure and the sound insulation structure 5, but also provided at the connection between the acoustic meta-material sound absorbing structure and the sound insulation structure 5 and other rigid parts. The elastic member 6 is provided at the connection part to reduce the vibration transmission between the connections.

[0087] It should be noted that in the embodiment of the present invention, the elastic member 6 is a rubber plate, which is installed between the acoustic meta-material sound absorption structure and the sound insulation structure 5 and the inner wall of the assembled shell to reduce the vibration transmission between the hard connections. Figure 1 For example, the thickness of the rubber sheet in the embodiment of the present invention is preferably 1 mm.

[0088] Specifically, the sound insulation structure 5 in the embodiment of the present invention is made of calcium silicate board, and the thickness of the calcium silicate board is 6 mm. The full-band high-efficiency noise reduction device structure provided by the present invention, the sound insulation structure 5 is a calcium silicate board, which has excellent high-frequency sound insulation performance and fire resistance.

[0089] Specifically, the acoustic meta-material sound absorbing structure in the embodiment of the present invention is composed of a honeycomb structure 2 and a shell 1. The honeycomb structure 2 is built into the shell 1 using an adhesive 3. The adhesive 3 in the embodiment of the present invention is epoxy glue. The thickness of the acoustic meta-material sound absorbing structure is 50 mm, and the thickness of the shell 1 is 1 mm. The full-band high-efficiency noise reduction device structure provided by the present invention uses an epoxy glue with high weather resistance and high stability as the adhesive 3 to fix the acoustic meta-material sound absorbing structure and ensure the service life.

[0090] In the full-band high-efficiency noise reduction device structure provided by the present invention, the honeycomb structure 2 and the shell 1 are both made of aluminum structures, and have certain mechanical properties as well as good weather resistance and environmental protection performance.

[0091] Specifically, Figure 5 and Figure 6 As shown, the sound absorption and insulation structure in the embodiment of the present invention is built into the assembly shell 8, and the assembly shell 8 is a rectangular shell with an opening on the top, wherein the hole of the acoustic meta-material sound absorption structure faces the sound source side through the opening of the assembly shell. The side of the assembly shell 8 is provided with an opening, and the sound absorption and insulation structure is installed into the interior of the assembly shell 8 through the opening. The bottom of the assembly shell 8 extends outward to form a flange frame 7. The assembly shell 8 and the flange frame 7 form a modular noise reduction device for modular processing and installation.

[0092] In the embodiment of the present invention, the elastic member 6 is not only arranged between the acoustic meta-material sound absorption structure and the sound insulation structure 5, but can also be arranged on the inner wall of the assembly shell 8 to reduce the vibration transmission between the hard connections. The thickness of the assembly shell 8 is 1mm, and the thickness of the outer flange 7 of the assembly shell 8 is 2mm. In order to reduce the vibration transmission between the hard connections, the elastic member 6 is pasted between the two, and the thickness of the rubber sheet is 1mm. The assembly shell 8 in the embodiment of the present invention is to assemble the acoustic meta-material sound absorption structure and the sound insulation structure 5, so that the noise reduction device becomes a whole, which is convenient for modular processing and installation, and is also easy to install.

[0093] The full-band substation equipment noise reduction device provided in the embodiment of the present invention, wherein the honeycomb structure 2 and the shell 1 form a sound absorption layer to absorb noise, and the sound insulation structure, elastic parts, and assembled shell form a sound insulation layer to reflect noise. In order to adapt to the noise reduction of equipment of different sizes, if the equipment is large, but the required noise reduction device is small in size, it is necessary to assemble the substation equipment noise reduction device in the embodiment of the present invention, and a steel column frame can be installed on the outside of the substation equipment, and the substation equipment noise reduction device in the embodiment of the present invention can be installed on the steel column frame until the entire substation equipment is wrapped. The flap frame 7 is provided with an opening, and the substation equipment noise reduction device can be installed on the steel column frame by bolts. The flap frame 7 can fix the substation equipment noise reduction device on the column. The substation equipment noise reduction device in the embodiment of the present invention is generally placed 20-30cm outside the sound source equipment of the substation equipment noise reduction device.

[0094] The number of Helmholtz resonance cavities of the acoustic metamaterial sound-absorbing structure in the embodiment of the present invention is adapted to the size of the substation equipment. The size of a single cavity unit is calculated according to the above formula, and then the number of cavities is set according to the size of the substation equipment to be noise reduced. The acoustic metamaterial sound-absorbing structure can cover the propagation path of the noise of the substation equipment at a preset position.

[0095] In the embodiment of the present invention, the sound absorption coefficients of the noise reduction device for substation equipment at 100 Hz, 200 Hz, and 315 Hz are 0.40, 0.42, and 0.54 respectively, and the sound insulation reaches 39 dB.

[0096] As an alternative implementation, when the thickness of the acoustic metamaterial sound-absorbing structure in the embodiment of the present invention is 68 mm and the thickness of the calcium silicate board is 10 m, the sound absorption coefficients of the substation equipment noise reduction device at 100 Hz, 200 Hz, and 315 Hz are 0.39, 0.41, and 0.55 respectively, and the sound insulation reaches 40 dB.

[0097] As an alternative implementation, when the thickness of the acoustic metamaterial sound-absorbing structure in the embodiment of the present invention is 45 mm, the thickness of the calcium silicate board is 8 mm, and the aperture of the opening on the side of the assembled shell facing the sound source is 8 mm, the sound absorption coefficients of the substation equipment noise reduction device at 100 Hz, 200 Hz, and 315 Hz are 0.37, 0.42, and 0.53 respectively, and the sound insulation reaches 38 dB.

[0098] As an alternative implementation, when the thickness of the acoustic metamaterial sound-absorbing structure in the embodiment of the present invention is 60 mm, the thickness of the calcium silicate board is 8 mm, and the aperture of the opening on the side of the assembled shell facing the sound source is 14 mm. The sound absorption coefficients of the substation equipment noise reduction device at 100 Hz, 200 Hz, and 315 Hz are 0.38, 0.43, and 0.53 respectively, and the sound insulation reaches 39 dB.

[0099] Comparative Example 1 (Compared with Example 2, the acoustic metamaterial sound absorbing structure is replaced by rock wool)

[0100] Select density 100kg / m 3 , rock wool with a thickness of 50 mm replaces the acoustic metamaterial sound absorption structure in Example 1, and the sound absorption coefficients of the noise reduction device at 100 Hz, 200 Hz, and 315 Hz are 0.12, 0.31, and 0.40 respectively, and the sound insulation reaches 37 dB.

[0101] Comparative Example 2 (Compared with Example 2, the acoustic metamaterial sound absorbing structure is replaced by glass wool felt)

[0102] Select density 100kg / m 3 , glass wool with a thickness of 50 mm replaces the acoustic metamaterial sound absorption structure in Example 1, and the sound absorption coefficients of the noise reduction device at 100 Hz, 200 Hz, and 315 Hz are 0.05, 0.14, and 0.32 respectively, and the sound insulation reaches 36 dB.

[0103] Comparative Example 3 (Compared with Example 2, the acoustic metamaterial sound absorbing structure is replaced by centrifugal glass wool felt)

[0104] Select density 24kg / m 3 The centrifugal glass wool felt with a thickness of 50 mm replaces the acoustic metamaterial sound absorption structure in Example 1. The sound absorption coefficients of the noise reduction device at 100 Hz, 200 Hz, and 315 Hz are 0.27, 0.36, and 0.50, respectively, and the sound insulation reaches 38 dB.

[0105] Comparative Example 4 (Compared with Example 2, the acoustic metamaterial sound absorbing structure is replaced by aluminum silicate felt)

[0106] Select density 50kg / m 3 The acoustic meta-material sound-absorbing structure in Example 1 is replaced by aluminum silicate wool felt with a thickness of 50 mm. The sound absorption coefficients of the noise reduction device at 100 Hz, 200 Hz, and 315 Hz are 0.26, 0.35, and 0.48, respectively, and the sound insulation reaches 38 dB.

[0107] By comparing the sound absorption coefficients of Comparative Examples 1 to 4 with the sound absorption coefficients of the substation equipment noise reduction device provided with an acoustic metamaterial sound absorption structure in the embodiment of the present invention, the substation equipment noise reduction device in the embodiment of the present invention can effectively absorb and isolate the low-frequency noise and high-frequency noise generated by the substation equipment.

[0108] In addition, it should be understood that although this specification is described in accordance with the implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation modes that can be understood by those skilled in the art. The above content is only to illustrate the technical idea of ​​the present invention, and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution according to the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. An acoustic metamaterial sound absorbing structure, characterized in that: It comprises two shells arranged in parallel with each other and a honeycomb structure arranged in the two shells; The honeycomb structure includes a plurality of cavity units, which are periodically and continuously arranged, the opening of each cavity unit faces one of the shells, and a hole is provided at a position corresponding to the opening of each cavity unit, and the cavity unit, the two shells and the hole form a Helmholtz resonance cavity.

2. The acoustic metamaterial sound absorbing structure according to claim 1, characterized in that: The hole is located at the center of the cavity unit.

3. The acoustic metamaterial sound absorbing structure according to claim 1, characterized in that: The holes are divided into first holes and second holes, the diameter of the first holes is larger than the diameter of the second holes; and the first holes and the second holes are alternately distributed.

4. The acoustic metamaterial sound absorbing structure according to claim 3, characterized in that: An insertion tube extending into the cavity unit is fixed on the second hole.

5. The acoustic metamaterial sound absorbing structure according to claim 1, characterized in that: The cross-sectional shape of the cavity unit includes a regular hexagon, a parallelepiped or an axisymmetric hexagon.

6. The acoustic metamaterial sound absorbing structure according to claim 1, characterized in that: The cavity unit and the shell are made of aluminum-manganese alloy.

7. The acoustic metamaterial sound absorbing structure according to claim 1, characterized in that: The sound absorption coefficient calculation formula of the Helmholtz resonance cavity is: Where α is the sound absorption coefficient of a single Helmholtz resonance cavity; Z s is the surface acoustic impedance of the Helmholtz resonance cavity.

8. The acoustic metamaterial sound absorbing structure according to claim 7, characterized in that: The surface acoustic impedance Z of the Helmholtz resonance cavity s The calculation formula is: WITH s =δ2(Z′ n / φ+Z c ) / Z0; In the formula, δ2 is the correction coefficient of the cavity wall thickness on the acoustic impedance, δ2 = S A / S c , S A is the cross-sectional area of ​​the external cavity, S c is the cross-sectional area of ​​the internal air cavity, φ is the perforation rate, φ=S e / S c , S e is the cross-sectional area of ​​the insertion tube, Z n ' is the characteristic impedance of the end of the insertion tube; Z c is the cavity characteristic impedance of the Helmholtz resonance cavity; Z0 is the characteristic impedance of air.

9. The acoustic metamaterial sound absorbing structure according to claim 8, characterized in that: The characteristic impedance Z of the insertion tube end n The calculation formula of ' is: In the formula, Z n is the insertion tube impedance; y is a dimensionless constant representing the ratio of the insertion tube radius to the viscous boundary thickness, d is the diameter of the insertion tube; μ0 is the kinematic viscosity of the air, j is the imaginary unit, ω is the angular frequency, ω=2πf, f is the sound wave frequency, and ρ0 is the air density.

10. The acoustic metamaterial sound absorbing structure according to claim 9, characterized in that: The insertion tube impedance Z n The calculation formula is: Where j is an imaginary unit, ω is the angular frequency, ω=2πf, f is the sound wave frequency, ρ0 is the air density, l is the height of the entire insertion tube, ν0 is the air viscosity, ν0=μ0 / ρ0, μ0 is the kinematic viscosity of the air, Λ is the viscous characteristic length, q0=μ0 / σ,α ∞ is the curvature, χ is the curvature coefficient, σ is the static flow resistivity, σ=32μ0 / d 2 , d is the diameter of the insertion tube.

11. The acoustic metamaterial sound absorbing structure according to claim 8, characterized in that: The cavity characteristic impedance Z of the Helmholtz resonance cavity c The calculation formula is: From c =-jZ0cot(k0δ1h) Where j is an imaginary unit, ω is the angular frequency, Z0 is the characteristic impedance of air, Z0 = ρ0c0, ρ0 and c0 are air density and sound speed respectively, k0 is the air wave number, k0 = ω / c0, δ1 = (V c -V e ) / V c , V c is the air volume of the cavity, V e is the volume of air in the inserted tube, V c =S c (L-2t1), V e =S e (l e -t1), S e is the cross-sectional area of ​​the insertion tube, S c is the cross-sectional area of ​​the internal air cavity, t1 is the cavity thickness, L is the height of the cavity, l e represents the overall height of the insertion tube, δ1 is the correction coefficient considering the effect of the total surface of the cavity on the acoustic impedance, and h is the height of the insertion tube in the cavity.

12. A noise reduction device for substation equipment, characterized in that: It comprises an acoustic metamaterial sound absorbing structure as described in any one of claims 1 to 11, and a sound insulation structure fixed to the bottom of the acoustic metamaterial sound absorbing structure; the hole on the shell of the acoustic metamaterial sound absorbing structure faces the sound source side.

13. A noise reduction device for substation equipment according to claim 12, characterized in that: An elastic member is fixed between the acoustic metamaterial sound absorbing structure and the sound insulating structure.

14. A noise reduction device for substation equipment according to claim 12, characterized in that: The acoustic metamaterial sound absorbing structure and the sound insulating structure are installed inside an assembled shell, and the assembled shell is a rectangular shell with an opening on the top.

15. A noise reduction device for substation equipment according to claim 14, characterized in that: The bottom of the assembled shell extends outward to form a flange.

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